The low density of TNOs is due partly to their composition, as the H2O content of these distant objects is significantly higher than those in the inner Solar system, but it is also due to their higher porosity. In the case of smaller TNOs, when the radius does not exceed \(\sim \) 150 km, the porosity can reach 60% [1]}. Such a high porosity is only possible if they formed after the decay of \(^{26}\) Al to maintain their high porosity as there is no internal transformation by heat at this stage.
In the absence of accurate knowledge of the internal composition, a simplified composition was used, which has been used in previous serpentinization studies [2]}, [3]}.
